I was told my machanic that my exhaust is running really hot. He said it could be that I had faulty injectors but I just had then looked and and were fine. I also replaced the fuel filter but I want to know if anyone knows wat I should do. do i need to adjust the air fuel ratio? is so how can I do it?

 

Even if you could adjust the A/F ratio (by increasing the duration of the injector opening) how would you know what to adjust it to. You would need access to a CO tester to determine your present A/F ratio and that would have to be at various loads which can only be done on a dyno or on the road if the CO monitor can be portable. If you are running that hot you can take a hard run at full operating temperature then pull the plugs and examine them. The color of the ceramic under the electrode will tell you if you're running lean or not, it will also tell you which cylinder. I would go on the internet (spark plug manufacturer) to get a picture of what the color looks like. Did the mechanic do a CO test? If not he may be only trying to engineer some injector business. I would also think that if you are running that lean you would get a computer code from the Oxy sensor. Do you have any codes?

 

I dont have any codes right now. What is a CO test? Also if I am running lean wouldnt I be getting great gas mileage? If the injectors are find do you think that maybe I have a hole somewhere in the intake after the MAS that is getting it to run hot.

 

I think if you were running that lean you should get a code. A CO test is Carbon Monoxide. By determining the amount (%) of CO you can determine the A/F ratio. See http://www.perfectpower.com/Technical_info/afr.asp
Yes your gas mileage would be better but are you keeping that close watch? Do you log your mileage at every fill or do you just feel it is better? Modern cars run a bit lean anyway. If 14:1 is perfect 13:1 would be richer, 15:1 would be leaner, just an example, not to be taken as good figures. I think if you are sucking air after the MAS you would not ldle or run good. The car should stumble at idle. Replacing the fuel filter will only restore fuel pressure if it is plugged. I would suspect that if it were plugged you could run at low throttle slow speeds, but falter at high throttle high speeds.

 

the stock ecu is designed find the right airfuel ratio while in closed loop mode (every day driving) it uses the o2 sensor, decides whether your car is running rich or lean at that instant, and adjusts the amount of fuel it delivers accordingly. It does this many times per second. If your car is running hot (lean) you may need a new 02 sensor, have clogged injectors, or need a new fuel pump, but you dont need to buy something to tune your car with. Thats asking for trouble, and is just going to be a bandaid until you find the problem.